System and method for fitting a hearing prosthesis sound processor using alternative signals

ABSTRACT

Alternative stimuli, i.e., stimuli other than the constant amplitude stimuli used in prior fitting schemes, are used to set the parameters of a hearing prosthesis, such as a cochlear implant system. The use of such alternative stimuli allows the entire fitting process to be completed in a very short time period, and generally eliminates the need for secondary adjustments. In one preferred embodiment, the alternative stimuli comprise white noise that is internally generated within the speech processor.

This application is a Continuation of U.S. patent application Ser. No.12/250,512, filed Oct. 13, 2008, which is a Continuation of Ser. No.10/651,653, filed Aug. 29, 2003, which claims the benefit of U.S.Provisional Application Ser. No. 60/407,173, filed Aug. 30, 2002, whichapplications are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to hearing prostheses, and moreparticularly to an improved technique for programming, or fitting, acochlear implant system to a particular patient.

Cochlear prostheses produce sensations of sound in deaf patients bydirect electrical stimulation of the auditory nerve. In modern,multichannel cochlear prostheses, several different sites are stimulatedat various distances along the cochlea to evoke the different pitches ofsound perception that are normally encoded by nerve activity originatingform the respective sites. The patterns of electrical stimulation arederived from acoustic signals picked up by a microphone and transformedby a so-called speech processor that is programmed to meet theparticular requirements of each patient. Several different schemes forprocessing the acoustic signal and transforming it into electricalstimuli have been developed and are well-described in the scientificliterature and various patents. For purposes of the present invention,these schemes—also known as speech processing strategies—can generallybe considered as either sequentially, partially-simultaneously orfully-simultaneously speech processing strategies.

The conventional setting of electrical stimulation levels in soundprocessors for cochlea implant systems—a process generally referred toas “fitting” the speech processor to a patient—has involved thestimulation of single channels (comprised of monopolar or bipolarstimulation pathways) employing stimuli that do not resemble thestimulation patterns inherent in the on-going speech signal. See, e.g.,U.S. Pat. No. 5,626,629, incorporated herein by reference. Typically,during such fitting process, gated-bursts of some fixed burst durationand constant amplitude are delivered to the patient. This procedure ofobtaining psychophysical measurements is often quite laborious. Thepatient's task is to set a level where sound is barely audible, and thenset a level where sound is comfortably loud.

Disadvantageously, after going through the time-consuming and laboriouscochlear-implant-fitting process, when the patient's microphone isenabled and speech stimuli are delivered to all channels, eithersequentially, partially-simultaneously or fully-simultaneously, thepsychophysically set levels bear little resemblance to the finalparameters set in the patient's sound processor. Adjustments to theoverall level of stimulation as well as other parameters tend to berequired to mold the psychophysically derived parameters into a viableprogram that appropriately maps the perceived speech stimuli toelectrical stimuli that may be delivered directly to the patient'scochlea. Hence, essentially two fitting procedures are typicallyrequired—one to set the psychophysical levels, and a second to makeadjustments to such levels.

A further complication in setting levels in a sound processor is thefact that in cochlear-implant systems, which employ narrow pulse widths(e.g., 10.7 microseconds) and high rates of stimulation, obtainingsingle-channel measurements for estimates of comfortable loudness is notpractical. At high rates of stimulation, the behavior of theelectrically stimulated auditory system can mimic that of the normallyhealthy ear in that perception of constant amplitude stimuli cannot bemaintained over time by all patients. Thus, the need arises, in settingthe levels in cochlear implant processors, for using either actualspeech stimuli, or stimuli that mimic the nature of speech.

SUMMARY OF THE INVENTION

The present invention addresses the above and other needs by usingalternative stimuli, i.e., stimuli other than the constant amplitudestimuli used in prior fitting schemes, to set the parameters of acochlear implant system. The use of such alternative stimuliadvantageously allows the entire fitting process to be completed in avery short time period, and generally eliminates the need for secondaryadjustments.

In accordance with one aspect of the present invention, modulated pulsetrains with selectable degrees of amplitude modulation are deliveredduring the fitting process. These novel stimuli are delivered to thecochlear processor either in rapid sequential fashion, partiallysimultaneous fashion, or full simultaneous fashion to groups of channelswithin the speech processor. In this context, a “group” of channels maycontain n channels, where n is an integer that may be as few as onechannel or as large as the number of channels within the speechprocessor of the cochlear implant system. Advantageously, such modulatedpulse trains mimic the time varying nature of speech stimulisufficiently so as to allow the setting of the sound processorparameters in a single step without further adjustments.

In accordance with another aspect of the invention, various speech-likestimuli may be inputted during the fitting process in order to set theparameters of the sound processor. Such speech-like stimuli include, butare not necessarily limited to: (1) shaped bands of noise whose overallbandwidth is adjustable; (2) modulated bands of noise whose centerfrequencies are adjustable; (3) complex tonal stimuli whose spectra andvarious amplitude components are adjustable; or (4) speech tokens whosespectra and amplitude envelopes are well described.

In accordance with an additional aspect of the invention, modulatedstimuli, in some embodiments, may be delivered directly through theband-pass filters of the sound processor via the fitting system ratherthan through an auxiliary port. The perceived loudness of such stimulimay then be adjusted as needed, e.g., according to prior knownpsychophysical procedures.

In accordance with yet another feature of the invention, in oneembodiment, the modulated stimuli comprise white noise that is generatedinternal to the speech processor. Such white noise is then applieddirectly through the band-pass filters of the sound processor andprocessed through a multiplicity of channels in parallel so that stimuliresulting from the white noise are delivered to a selected group ofelectrodes, where the perceived loudness of the stimuli are adjusted asneeded to a desired threshold level.

Advantageously, in some embodiments of the invention, the stimuli usedby the invention during the sound processor setting procedure may begenerated through a software module that may be incorporated into thecochlear implant processor fitting system, e.g., the CLARION® CII BionicEar® System, or the HiRes90K® System, available commercially fromAdvanced Bionics Corporation, of Sylmar, Calif., or othercommercially-available cochlear implant systems.

In operation, at least some embodiments of the invention may adjust thelevel of the delivered stimuli according to known perceptual loudnesscontours derived from normal hearing individuals (minimal audible field)or from known acoustic phenomena, such as the long-term spectrum ofspeech. Thus, e.g., stimuli may be delivered at the electricalequivalent of the long-term spectrum of speech, at a level representingthe detection abilities of normal hearing individuals, or at any pointin between.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will be more apparent from the following more particulardescription thereof, presented in conjunction with the followingdrawings wherein:

FIG. 1 is a current stimulation waveform that defines the stimulationrate (1/T) and biphasic pulse width (PW) associated with electricalstimuli, as those terms are used in the present application;

FIGS. 2A and 2B respectively show a cochlear implant system and apartial functional block diagram of the cochlear stimulation system,which system is capable of providing high rate pulsatile electricalstimuli;

FIG. 3 illustrates application of speech-like stimuli, e.g., anamplitude modulated high rate pulsatile waveform, during the fittingprocess of a cochlear implant system in accordance with the invention;

FIGS. 4A and 4B show respective fitting configurations that may be usedduring a fitting session;

FIG. 5 illustrates a preferred configuration for applying speech-likestimuli to the speech processor of a cochlear implant system during afitting session; and

FIG. 6 illustrates a preferred configuration for applying noise stimulito selected multiple channels of the cochlear implant system during afitting session.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best mode presently contemplated forcarrying out the invention. This description is not to be taken in alimiting sense, but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe determined with reference to the claims.

FIG. 1 shows a waveform diagram of a biphasic pulse train, and definesstimulation rate, pulse width and pulse amplitude.

FIG. 2A shows a cochlear stimulation system that includes a speechprocessor portion 10 and a cochlear stimulation portion 12. The speechprocessor portion 10 includes a speech processor (SP) 16 and amicrophone 18. The microphone 18 may be connected directly to the SP 16,or may be coupled to the SP 16 through an appropriate communication link24. An auxiliary input port 17 may also be part of the speech processor16 to allow input signals from a source other than the microphone 18 tobe input into the SP 16.

The cochlear stimulation portion 12 includes an implantable cochlearstimulator (ICS) 21 and an electrode array 48. The electrode array 48 isadapted to be inserted within the cochlea of a patient. The array 48includes a multiplicity of electrodes, e.g., sixteen electrodes, spacedalong its length, that are selectively connected to the ICS 21. Theelectrode array 48 may be substantially as shown and described in U.S.Pat. No. 4,819,647 or 6,129,753, incorporated herein by reference.Electronic circuitry within the ICS 21 allows a specified stimulationcurrent to be applied to selected pairs or groups of the individualelectrodes included within the electrode array 48 in accordance with aspecified stimulation pattern, defined by the SP 16.

The ICS 21 and the SP 16 are shown in FIG. 2A as being linked togetherelectronically through a suitable data or communications link 14. Insome cochlear implant systems, the SP 16, auxiliary input port 17 andmicrophone 18 comprise the external portion of the cochlear implantsystem; and the ICS 21 and electrode array 48 comprise the implantableportion of the system. Thus, the data link 14 is a transcutaneous datalink that allows power and control signals to be sent from the SP 16 tothe ICS 21. In some embodiments, data and status signals may also besent from the ICS 21 to the SP 16.

In recent cochlear implant systems, as shown more particularly below inFIG. 2B, at least certain portions of the SP 16 are included within theimplantable portion of the overall cochlear implant system, while otherportions of the SP 16 remain in the external portion of the system. Ingeneral, at least the microphone 18 (and auxiliary input port 17, ifused) and associated analog front end (AFE) circuitry 22 will be part ofthe external portion of the system; and at least the ICS 21 andelectrode array 48 are part of the implantable portion of the invention.As used herein, “external” means not implanted under the skin orresiding within the inner ear. However, “external” may mean within theouter ear, including in the ear canal, and may also include within themiddle ear.

Typically, where a transcutaneous data link must be established betweenthe external portion and implantable portions of the system, such linkis realized by an internal antenna coil within the implantable portion,and an external antenna coil within the external portion. In use, theexternal antenna coil is positioned so as to be aligned over thelocation where the internal antenna coil is implanted, allowing suchcoils to be inductively coupled to each other, thereby allowing data(e.g., the magnitude and polarity of a sensed acoustic signals) andpower to be transmitted from the external portion to the implantableportion. Note, in other embodiments of the invention, both the SP 16 andthe ICS 21 may be implanted within the patient, either in the samehousing or in separate housings. If in the same housing, the link 14 maybe realized with a direct wire connection within such housing. If inseparate housings, as taught, e.g., in U.S. Pat. No. 6,067,474,incorporated herein by reference, the link 14 may be an inductive linkusing a coil or a wire loop coupled to the respective parts.

The microphone 18 senses acoustic signals and converts such sensedsignals to corresponding electrical signals, and may thus be consideredas an acoustic transducer. The electrical signals are sent to the SP 16over a suitable electrical or other link 24. Alternatively, electricalsignals may be input directly into the auxiliary input port 17 from asuitable signal source. The SP 16 processes the converted acousticsignals received from the microphone, or the electrical signals receivedthrough the auxiliary input port 17, in accordance with a selectedspeech processing strategy in order to generate appropriate controlsignals for controlling the ICS 21. In operation, such control signalsspecify or define the polarity, magnitude, location (which electrodepair receives the stimulation current), and timing (when the stimulationcurrent is applied to the electrode pair) of the stimulation currentthat is generated by the ICS. Such control signals thus combine toproduce a desired spatiotemporal pattern of electrical stimuli inaccordance with the desired speech processing strategy. Unlike earlycochlear implant systems, more modern cochlear implant systemsadvantageously confine such control signals to circuitry within theimplantable portion of the system, thereby avoiding the need tocontinually send or transmit such control signals across atranscutaneous link.

The speech processing strategy is used, inter alia, to condition themagnitude and polarity of the stimulation current applied to theimplanted electrodes of the electrode array 48. Such speech processingstrategy involves defining a pattern of stimulation waveforms that areto be applied to the electrodes as controlled electrical currents. Inaccordance with the present invention, an auto-conditioning with highresolution (ACHR) strategy is used which stimulates the implantedelectrodes with a high rate pulsatile pattern that is amplitudemodulated by the sound information. If multiple electrode pairs exist,as is the case with a multichannel cochlear implant system, then thetypes of stimulation patterns applied to the multiple channels may beconveniently categorized as: (1) simultaneous stimulation patterns, or(2) non-simultaneous stimulation patterns. Simultaneous stimulationpatterns may be “fully” simultaneous or partially simultaneous. A fullysimultaneous stimulation pattern is one wherein stimulation currents,either analog or pulsatile, are applied to the electrodes of all of theavailable channels at the same time. A partially simultaneousstimulation pattern is one wherein stimulation currents, either analogor pulsatile, are applied to the electrodes of two or more channels, butnot necessarily all of the channels, at the same time. Examples of eachtype are given in U.S. Pat. No. 6,289,247, incorporated herein byreference.

Analog waveforms used in analog stimulation patterns are typicallyreconstructed by the generation of continuous short monophasic pulses(samples). The sampling rate is selected to be fast enough to allow forproper reconstruction of the temporal details of the signal. An exampleof such a sampled analog stimulation pattern is a simultaneous analogsampler (SAS) strategy.

Current pulses applied in pulsatile stimulation patterns are generallybiphasic pulses, as shown in FIG. 1, but may also be multiphasic pulses,applied to the electrodes of each channel. The biphasic/multiphasicpulse has a magnitude (e.g., amplitude and/or duration) that varies as afunction of the sensed acoustic signal. (A “biphasic” pulse is generallyconsidered as two pulses: a first pulse of one polarity having aspecified magnitude, followed immediately, or after a very short delay,by a second pulse of the opposite polarity having the same total charge,which charge is the product of stimulus current times duration of eachpulse or phase.) For multichannel cochlear stimulators of the type usedwith the present invention, it is common to apply a high rate biphasicstimulation pulse train to each of the pairs of electrodes of selectedchannels in accordance with a selected strategy, and modulate the pulseamplitude of the pulse train as a function of information containedwithin the sensed acoustic signal, or the received auxiliary inputsignal.

Turning next to FIG. 2B, a partial block diagram of a representativecochlear implant is shown. More particularly, FIG. 2B shows a partialfunctional block diagram of the SP 16 and the ICS 21 of an exemplarycochlear implant system capable of providing a high rate pulsatilestimulation pattern. That which is shown in FIG. 2B depicts thefunctions that are carried out by the SP 16 and the ICS 21. The actualelectronic circuitry that is used to carry out these functions is notcritical to understanding and practicing the present invention. Itshould also be pointed out that the particular functions shown in FIG.2B are representative of just one type of signal processing strategythat may be employed (which divides the incoming signal into frequencybands, and independently processes each band). Other signal processingstrategies could just as easily be used to process the incomingacoustical signal.

A complete description of the functional block diagram of the cochlearimplant system shown in FIG. 2B is generally found in U.S. Pat. No.6,219,580, incorporated herein by reference. It is to be emphasized thatthe functionality shown in FIG. 2B is only representative of one type ofexemplary cochlear implant system, and is not intended to be limiting.The details associated with a given cochlear implant system are notcritical to understanding and practicing the present invention.

One important addition to the functional block diagram of the cochlearimplant system illustrated in FIG. 2B that may be used by the presentinvention, which is not shown or described in the U.S. Pat. No.6,219,580, is the use of an internal signal injection port 31. Such port31 allows appropriate internal signals, generated within the speechprocessor circuits, to be injected into the signal processing pathimmediately after the AGC circuit 29. This port differs from theexternal auxiliary port 17 in that it is not intended for use byexternal signals, and the internal signals applied to it are notprocessed by the AFE circuits 22, the A/D circuits 28, or the AGCcircuits 29, as are signals received through the auxiliary input port 17or the microphone 18. Thus, for example, an appropriateinternally-generated signal may be generated by appropriate circuitsincluded within the speech processor circuits 16 and applied to theinternal signal injection port 31, and thereafter be processed by thespeech processor circuits and other circuits (e.g., pulse generatorcircuits) within the cochlear implant system in order to facilitatefitting of the cochlear implant system to a particular patient or user.As will be described in more detail below in conjunction with thedescription of FIG. 6, one preferred embodiment of the invention applieswhite noise, generated by circuits within the speech processor, to theinternal injection port 31, and then processes such noise throughselected bands or groups of channels simultaneously, resulting in noisestimuli being applied to multiple electrodes simultaneously. Being ableto sense noise stimuli on multiple electrodes in this fashion allows the“M” levels of the patient to be quickly identified and set during afitting session.

In the manner described in the U.S. Pat. No. 6,219,580, the cochlearimplant functionally shown in FIG. 2B provides n analysis channels thatmay be mapped to one or more stimulus channels. That is, as seen in FIG.2B, after the incoming sound signal is received through the microphone18 or auxiliary input port 17, and the analog front end circuitry (AFE)22, it is digitized in an analog to digital (A/D) converter 28, and thensubjected to appropriate gain control (which may include compression) inan automatic gain control (AGC) unit 29. (It should be noted that insome instances the signal input into the auxiliary input port 17 mayalready be digitized, in which case a signal path 19 is provided thatbypasses the A/D converter 28.) After appropriate gain control, thesignal is divided into n analysis channels, each of which includes abandpass filter, BPFn, centered at a selected frequency. The signalpresent in each analysis channel is processed as described more fully inthe U.S. Pat. No. 6,219,580, and the signals from each analysis channelare then mapped, using mapping function 41, so that an appropriatestimulus current, of a desired amplitude and timing, may be appliedthrough a selected stimulus channel to stimulate the auditory nerve.

Thus it is seen that the system of FIG. 2B provides a multiplicity ofchannels, n, wherein the incoming signal is analyzed. The informationcontained in these n “analysis channels” is then appropriatelyprocessed, compressed and mapped in order to control the actual stimuluspatterns that are applied to the patient by the ICS 21 and itsassociated electrode array 48. The electrode array 48 includes amultiplicity of electrode contacts, connected through appropriateconductors, to respective current generators, or pulse generators,within the ICS. Through this multiplicity of electrode contacts, amultiplicity of stimulus channels, e.g., m stimulus channels, existthrough which individual electrical stimuli may be applied at mdifferent stimulation sites within the patient's cochlea.

While it is common to use a one-to-one mapping scheme between theanalysis channels and the stimulus channels, wherein n=m, and the signalanalyzed in the first analysis channel is mapped to produce astimulation current at the first stimulation channel, and so on, it isnot necessary to do so. Rather, in some instances, a different mappingscheme may prove beneficial to the patient. For example, assume that nis not equal to m (n, for example, could be at least 20 or as high as32, while m may be no greater than sixteen, e.g., 8 to 16). The signalresulting from analysis in the first analysis channel may be mapped,using appropriate mapping circuitry 41 or equivalent, to the firststimulation channel via a first map link, resulting in a firststimulation site (or first area of neural excitation). Similarly, thesignal resulting from analysis in the second analysis channel of the SPmay be mapped to the second stimulation channel via a second map link,resulting in a second stimulation site. Also, the signal resulting fromanalysis in the second analysis channel may be jointly mapped to thefirst and second stimulation channels via a joint map link. This jointlink results in a stimulation site that is somewhere in between thefirst and second stimulation sites. The “in between site” is sometimesreferred to as a virtual stimulation site. Advantageously, thispossibility of using different mapping schemes between n SP analysischannels and m ICS stimulation channels to thereby produce a largenumber of virtual and other stimulation sites provides a great deal offlexibility with respect to positioning the neural excitation areas in alocation that proves most beneficial to the patient.

Still with reference to FIG. 2B, it should be noted that the speechprocessing circuitry 16 generally includes all of the circuitry frompoint (C) to point (A). In prior art cochlear implant systems, theentire SP circuitry was housed in a speech processor that was part ofthe external (or non-implanted) portion of the system. That is, in suchprior art systems, only the ICS 21, and its associated electrode array,were implanted, as indicated by the bracket labeled “Imp1” (for“Implant-1”). This means that in such prior art systems, the signalpassing through the serial data stream at point (A) is also the signalthat must pass through the transcutaneous communication link from theexternal unit to the implanted unit. Because such signal contains all ofthe defining control data for the selected speech processing strategy,for all m stimulation channels, it therefore has a fairly high data rateassociated therewith. As a result of such high data rate, either thesystem operation must be slowed down, which is generally not desirable,or the bandwidth of the link must be increased, which is also notdesirable because the operating power increases.

In contrast to prior art systems, a modern cochlear implant system, suchas the CII Bionic Ear® system, or the HiRes90K® system, manufactured byAdvanced Bionics Corporation of Sylmar, Calif., advantageously puts atleast a portion of the speech processor 16 within the implanted portionof the system. For example, a cochlear implant system may place thePulse Table 42 and arithmetic logic unit (ALU) 43 inside of theimplanted portion, as indicated by the bracket labeled “Imp2” in FIG.2B. Such partitioning of the speech processor 16 offers the advantage ofreducing the data rate that must be passed from the external portion ofthe system to the implanted portion. That is, the data stream that mustbe passed to the implanted portion Imp2 comprises the signal stream atpoint (B). This signal is essentially the digitized equivalent of themodulation data associated with each of the n analysis channels, and(depending upon the number of analysis channels and the sampling rateassociated with each) may be significantly lower than the data rateassociated with the signal that passes through point (A). Hence,improved performance without sacrificing power consumption may beobtained with a bionic ear implant.

Future generations of cochlear implant systems may incorporate more andmore of the speech processor 16 within the implanted portion of thesystem. For example, a fully implanted speech processor 16 wouldincorporate all of the SP in the implanted portion, as indicated by thebracket labeled Imp3 in FIG. 2B. Such a fully implanted speech processoroffers the advantage that the data input into the system, i.e., the datastream that passes through point (C), need only have rate commensuratewith the input signal received through the microphone 18 or theauxiliary input port 17.

With the preceding as background information relative to a typicalcochlear implant system, the present invention provides a streamlinedway of “fitting” such a cochlear implant system to a given patient. Moreparticularly, the present invention uses alternative stimuli, i.e.,stimuli other than the constant amplitude stimuli used in prior fittingschemes to determine “T” and “M” levels, see, e.g., U.S. Pat. Nos.5,626,629 and 6,289,247, incorporated herein by reference, to set theparameters of a cochlear implant system. The use of such alternativestimuli by the present invention advantageously allows the entirefitting process to be completed in a very short time period, andgenerally eliminates the need for secondary adjustments.

For example, as shown in FIG. 3, one embodiment of the present inventiongenerates modulated pulse trains with selectable degrees of amplitudemodulation. Such amplitude modulated pulse trains are delivered to thespeech processor during the fitting process either in rapid sequentialfashion, partially simultaneous fashion, or full simultaneous fashion togroups of channels within the speech processor. In this context, a“group” of channels may contain n channels, where n is an integer thatmay be as few as one channel or as large as the number of channelswithin the speech processor of the cochlear implant system.Advantageously, such modulated pulse trains mimic the time varyingnature of speech stimuli sufficiently so as to generally allow thesetting of the sound processor parameters in a single step withoutfurther adjustments on a channel-by-channel basis. Such modulated pulsetrains mimic the time varying nature of speech stimuli sufficiently soas to allow the setting of the sound processor parameters in a singlestep without further adjustments.

Thus, as seen in FIG. 3, a pulse generator 102 generates a stream ofpulses 101. The frequency of such stream of pulses 101 is preferablygreater than about 2 KHz. e.g., with a period T less than about 500microseconds (μsec). The pulse width, PW, is relatively narrow, e.g.,from about 11 μsec (e.g., 10.8 μsec) to about 75 μsec, but preferablyaround 21 μsec. Such pulses 101 are then amplitude modulated in amodulator 104 with a selected modulation signal 105, e.g., a signal thatprovides speech-like stimuli, to produce an amplitude modulated streamof pulses 103. The amplitude modulated stream of pulses 103 is thenapplied, e.g., on a channel-by-channel basis through an appropriatemultiplexer 106, or equivalent, or to groups of channels, to the inputsof the respective channels. Appropriate parameters associated with eachchannel are then adjusted, as the amplitude modulated pulsatile signal103 is applied to the channel, or to the channel group, to set theoperating parameters of the speech processor. After the fitting sessionis complete, and the needed operating parameters of the speech processorhave been set, the patient, or user of the cochlear implant system, isable to better perceive sound signals received through the microphone18, or auxiliary input port 17, as the appropriate sound.

The modulation signal 105 may take many forms. In one embodiment, forexample, the modulation signal mimics various speech-like stimuli. Suchspeech-like stimuli may include, for example, the following stimuli:

-   -   1. Shaped bands of noise whose overall bandwidth is adjustable.        These bands may be externally inputted into the auxiliary input        port 17 of the cochlear speech processor 16, or the internal        input port 31, at levels following the long-term spectrum of        speech in each band. For example, shaped bands of noise may be        used that cover the input center frequencies of 1, 3, 5 or more        channels.    -   2. Modulated bands of noise whose center frequencies are        adjustable.    -   3. Complex tonal stimuli whose spectra and various amplitude        components are adjustable.    -   4. Speech tokens whose spectra and amplitude envelopes are well        described.

Representative fitting system configurations that may be used with theinvention are illustrated in FIGS. 4A and 4B. The alternative stimuliprovided by the present invention in order to simplify the fittingprocess may be used with either of these fitting configurations, orother configurations.

As seen in FIG. 4A, there is shown a block diagram of the basiccomponents used to fit a given patient with a cochlear implant system.As seen in FIG. 4A, the implant system is as shown in FIG. 1, andincludes the SP 16 linked to an ICS 21, and the ICS is connected to anelectrode array 48. A microphone 18 is also linked to the SP 16 througha suitable communication link 24. A laptop computer 170, or other typeof computer, or equivalent device, is coupled to the speech processor 16through an interface unit (IU) 20, or equivalent device. The type oflinkage 23 established between the IU 20 and the SP 16 will varydepending upon whether the SP 16 is implanted or not. Any suitablecommunications link 23 may be used, as is known in the art, and thus thedetails of the link 23 are not important for purposes of the presentinvention. It should be noted that for some applications, the IU 20 maybe included within the computer 170 (e.g., as a communications interfacealready present within the computer, e.g., a serial port, or otherbuilt-in port, e.g., an IR port).

The computer 170, with or without the IU 20, provides input signals tothe SP 16 that simulate acoustical signals sensed by the microphone 18,or received through the auxiliary input port 17, and/or provide commandsignals to the SP 16. In some instances, e.g., when testing thepatient's threshold levels, the signals generated by the computer 170replace the signals normally sensed through the microphone 18. In otherinstances, e.g., when testing the patient's ability to comprehendspeech, the signals generated by the computer 170 provide commandsignals that supplement the signals sensed through the microphone 18.

The laptop computer 170 (or equivalent device) provides a display screen15 on which selection screens, stimulation templates and otherinformation may be displayed and defined. Such computer 170 thusprovides a very simple way for the audiologist or other medicalpersonnel, or even the patient, to easily select and/or specify aparticular pattern of stimulation parameters that may be thereafterused, even if for just a short testing period, regardless of whethersuch stimulation pattern is simple or complex. Also shown in FIG. 4A isa printer 19 which may be connected to the computer 170, if desired, inorder to allow a record of the selection criteria, stimulation templatesand pattern(s) that have been selected and/or specified to be printed.

FIG. 4B illustrates an alternative fitting system that may also be used.In FIG. 4B, the ICS 21 is linked to a speech processor configured oremulated within a palm personal computer (PPC) 11, such as a Palm Pilot,or equivalent processor, commercially available, e.g., from HewlettPackard. Such PPC 11 includes its own display screen 15′ on which somegraphical and textual information may be displayed. In use, the PPC 11is linked, e.g., through an infrared link 23′, to another computer, 170,as necessary. Typically, the functions of the SP and related devices arestored in a flashcard (a removable memory card that may be loaded intothe PPC 11), thereby enabling the PPC 11 to perform the same functionsof those elements encircled by the dotted line 13 in FIG. 4A. The PPC 11is coupled to the ICS 21 through a suitable data/power communicationslink 14′.

Advantageously, all of the stimuli used by the present invention duringthe sound processor setting procedure (or fitting process) may begenerated through a software module 110 that is incorporated into thecomputer 170, or equivalent processor, as illustrated generally in FIG.5. Moreover, as additionally illustrated in FIG. 5, and as a furthersimplification to the fitting process, the software module 110 may belinked directly to the auxiliary input port 17 of the speech processor16, thereby eliminating the need for an interface unit 20, or equivalentdevice (see FIG. 4A).

As a further variation of the invention, the software module, orequivalent processor, used to generate the stimuli used by the inventionmay be acoustically linked with the microphone 18 used by the speechprocessor 16 (see FIG. 4A). That is, the modulated stimuli used by theinvention may, in some embodiments, be inputted into the speechprocessor via the microphone link rather than through an interface unitor through the auxiliary port.

In operation, the level of the stimuli provided by the invention duringthe fitting process are adjusted according to known perceptual loudnesscontours derived from normal hearing individuals (minimal audible field)or from known acoustic phenomena, such as the long-term spectrum ofspeech. Thus, stimuli may be delivered at the electrical equivalent ofthe long-term spectrum of speech, at a level representing the detectionabilities of normal hearing individuals, or at any point in between.

Next, with reference to FIG. 6, a preferred manner of implementing afitting session in accordance with the invention is illustrated. As seenin FIG. 6, a pulse generator 102 generates a stream of pulses 101. Thefrequency of such stream of pulses 101 is preferably greater than about2 KHz. e.g., with a period T less than about 500 microseconds (μsec).The pulse width, PW, is relatively narrow, e.g., from about 5 μsec toabout 75 μsec, but preferably around 11 μsec (e.g., 10.8 μsec). Suchpulses 101 are then modulated in a modulator 104 with a noise signalgenerated by a noise generator 181. Preferably, the noise generator 181comprises a simple white noise generator realized using circuits alreadypresent within the implantable speech processor. The noise generator 181is controlled during a fitting session, e.g., turned ON or OFF, byprogram control circuitry 180. The pulse generator 102 is likewisecontrolled by the control circuitry 180.

The output signal from the modulator 104 comprises a pulse train ofwhite noise. This signal—a pulse train of white noise—is then processedsimultaneously through a multiplicity of channels within the speechprocessor, resulting in stimuli being applied to a first group, or band,of electrodes through electrode map circuitry 182. The electrode mapcircuitry 182 applies the signal at its input to a selected group ofelectrodes, E1, E2, E3, . . . Em, at its output. This mapping is, duringa fitting session, controlled by the program control circuitry 180.Advantageously, applicants have discovered that by applying the noisestimuli to multiple electrodes simultaneously, a better, moretrue-to-life, representation of how the patient will perceive actualsound, is obtained. Thus, during a fitting session, the “M” levels (thestimulation current amplitude that results in comfortable perceivedstimulation for each channel) for the group or band of channels wherethe noise stimuli are applied may be quickly determined and set.

By way of example, a typical fitting session using this embodiment ofthe invention may proceed as follows: (1) internally-generated whitenoise is generated and applied to the internal signal injection port;(2) the white noise is thereafter processed through a selected a firstgroup or band of channels, e.g., so as to cause stimuli to be generatedand applied to the patient through a first group or band of electrodes,e.g., electrodes E1, E2, E3 and E4; (3) the “M” levels (magnitude of theapplied stimuli) for the first group of channels are adjusted to acomfortable level as perceived by the patient or user; and (4) theprocess is repeated for a second group of channels, a third group ofchannels, and so on, until stimuli have been applied through all theelectrodes and all “M” levels have been set.

Electrode or channel groups (bands) used during this process may includeoverlapping channels or electrodes, i.e., an individual channel orelectrode may be present in more than one group or band. For example, afirst group of channels/electrodes may include electrodes E1, E2, E3,and E4; and a second group of channels/electrodes may include electrodesE3, E4, E5 and E6, a third group of channels/electrodes may includeelectrodes E5, E6, E7 and E8, and so on, with an overlap of twoelectrodes in each group or band. When such overlap exists, the “M”level of a particular channel may comprise an average of the “M” levelsdetermined from each group.

In one preferred rapid fitting session of a cochlear implant systemhaving sixteen channels and sixteen electrodes, there is no overlap ofelectrodes. Rather, white noise stimuli are first applied through afirst electrode group comprising electrodes E1, E2, E3 and E4 and the“M” level for each corresponding channel is determined jointly with theother channels/electrodes in the group based on what feels comfortableto the patient (user). Next, white noise stimuli are applied through asecond electrode group comprising electrodes E5, E6, E7 and E8, and the“M” level for each corresponding channel is again jointly determinedbased on patient perception. Next, white noise stimuli are appliedthrough a third electrode group comprising electrodes E9, E10, E11 andE12, and the “M” level for each corresponding channel is again jointlydetermined based on patient perception. Finally, white noise stimuli areapplied through a fourth electrode group comprising electrodes E13, E14,E15 and E16, and the “M” level for each corresponding channel is againjointly determined based on patient perception. Thus, in essentiallyfour steps, each of which can normally be performed and completed injust a matter of minutes, or even seconds, appropriate “M” levels (forsubsequent use by the cochlear stimulation system when sensing realsound through the microphone 18 and/or auxiliary port 17) may be set forall sixteen channels, thereby completing the fitting process.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations could be made thereto by those skilled in the art withoutdeparting from the scope of the invention set forth in the claims.

1. A method of adjusting parameter settings of a hearing prosthesisassociated with a particular patient comprising: generating modulatedpulse trains that have selectable degrees of modulation, do not have aconstant amplitude or frequency, and are configured to mimic the timevarying nature of speech stimuli; delivering the modulated pulse trainsto a sound processor of the hearing prosthesis during a “fitting”session; and using the modulated pulse trains to set the parametersettings of the hearing prosthesis during the “fitting” session withoutfirst determining a threshold level.
 2. The method of claim 1 whereinthe using of the modulated pulse trains to set the parameter settings ofthe hearing prosthesis is performed in a single step that requires nofurther adjustment to the parameter settings.
 3. The method of claim 1further including delivering the modulated pulse trains to the soundprocessor of the hearing prosthesis through a microphone coupled to thehearing prosthesis.
 4. The method of claim 1 further includingdelivering the modulated pulse trains to the sound processor of thehearing prosthesis through an auxiliary input of the hearing prosthesis.5. The method of claim 1 wherein the step of generating the modulatedpulse trains comprises generating speech-like stimuli selected from thegroup consisting of: a. shaped bands of noise whose overall bandwidth isadjustable, wherein said bands of noise are externally inputted to thesound processor at levels following a long-term spectrum of speech ineach band; b. modulated bands of noise whose center frequencies areadjustable; c. complex tonal stimuli whose spectra and various amplitudecomponents are adjustable; and d. speech tokens.
 6. The method of claim5 wherein the hearing prosthesis comprises a multi-channel hearingprosthesis hearing prosthesis having a multiplicity of channels, andwherein the shaped bands of noise are selected to cover input centerfrequencies of 1, 3, 5 or more of said multiplicity of channels.
 7. Themethod of claim 5 wherein the speech-like stimuli generated for useduring the sound processor setting procedure are generated with the aidof a software module incorporated into the hearing prosthesis.
 8. Themethod of claim 1 wherein the generating of the modulated pulse trainscomprises modulating pulse trains according to perceptual loudnesscontours derived from normal hearing individuals.
 9. The method of claim1 wherein the generating of the modulated pulse trains comprisesgenerating a pulse train and adjusting the level of the pulse trainbased on known acoustic phenomena.
 10. The method of claim 9 wherein theknown acoustic phenomena comprise a long-term spectrum of speech, andwherein the method further comprises using the modulated pulse trains torepresent an electrical equivalent of the long-term spectrum of speech.11. The method of claim 9 wherein the known acoustic phenomena comprisea long-term spectrum of speech, and wherein the method further comprisesusing the modulated pulse trains to represent the detection abilities ofnormal hearing individuals.
 12. The method of claim 9 wherein the knownacoustic phenomena comprise a long-term spectrum of speech, and whereinthe method further comprises using the modulated pulse trains torepresent any point between an electrical equivalent of the long-termspectrum of speech and detection abilities of normal hearingindividuals.
 13. The method of claim 1 further including delivering themodulated pulse trains to the sound processor of the hearing prosthesisby way of an interface unit connected to the hearing prosthesis.
 14. Asystem comprising: means for generating modulated pulse trains that haveselectable degrees of modulation, do not have a constant amplitude orfrequency, and are configured to mimic the time varying nature of speechstimuli; means for delivering the modulated pulse trains to a soundprocessor of a hearing prosthesis during a “fitting” session; and meansfor using the modulated pulse trains to set the parameter settings ofthe hearing prosthesis during the “fitting session” without firstdetermining a threshold level.
 15. The system of claim 14 wherein themeans for using the modulated pulse trains to set the parameter settingsof the hearing prosthesis is configured to set the parameter settings ina single step that requires no further adjustment.
 16. The system ofclaim 14 wherein the means for generating the modulated pulse trainscomprises means for generating speech-like stimuli selected from thegroup consisting of: a. shaped bands of noise whose overall bandwidth isadjustable, wherein said bands of noise are externally inputted to thesound processor at levels following a long-term spectrum of speech ineach band; b. modulated bands of noise whose center frequencies areadjustable; c. complex tonal stimuli whose spectra and various amplitudecomponents are adjustable; and d. speech tokens.